This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. MutY is an adenine DNA glycosylase that recognizes adenine nucleobase opposite 8-oxoguanine and catalyzes the cleavage of the N-glycosidic bond of the substrate 2'-deoxyadenosine. Although the previous X-ray crystallographic study provided significant insights into 8-oxoguanine recognition by MutY, the substrate adenine recognition and catalysis mechanisms by this enzyme are poorly understood, due in significant part to use of an enzymatically inactive MutY. Our program aims to shed light into these mechanisms by determining an X-ray structure of a catalytically active MutY bound to its inhibitor DNA.